So i'm sculpting and, sometimes, specially after i made a big change in the surface with any other brush, the smooth brush completely destroys the geometry that was there. This only happens after i've set dynotopo and changed the mesh, and if i turn it off, it stills creates the same problem. Every now and then if i enlarge the radius of the brush, it fixes it, but usually i have to take out any hard edge or lower a big bump that i made before and that seemed to have caused it. The weird thing is that it acts like that for the whole mesh and not just specific parts, and that sometimes it only happens when using my graphic tablet(as in the gif), but other times with both the tablet and the mouse.
It turns out, my pen tablet has the option to switch from Add to Substract, to do the opposite of what the brush was doing.
Whenever this happened was because I had it in substract mode, I didn't realize this because, in previous versions of Blender, Shift to smooth always smoothed stuff, but not anymore it seems.
Other person with similar problem: my tablet lists it as "pen or eraser" mode